An important issue in the operation of solid-state lighting devices, such as lighting devices employing LED sources, resides in the thermal management of the lighting device.
Performance of LED sources may be widely affected by the temperature reached by the junction in operation. A temperature increase in the junction may lead to a reduction of the luminous flux output from the LED.
The heat generated in operation by a light radiation source such as a LED source may be dissipated via a heat sink, which may be mounted on the rear side of the substrate carrying the source (it may be e.g. a substrate substantially similar to a Printed Circuit Board—PCB). Dissipation may be either active or passive, depending on the presence or absence of a fan or a blower.
In automotive applications, for instance, various heat sink solutions have been proposed.
For example, U.S. Pat. No. 7,082,032 B1 describes a heat sink device comprising a base and a plurality of fins connected to the base, the latter fins extending away from the base at an non-orthogonal angle to the base.
Document U.S. Pat. No. 6,533,028 B2 describes a heat sink having a plurality of fins disposed on a surface of a heat conducting plate, and being non-parallel to the heat receiving surface. An apparatus is also described comprising a heat sink together with a cooling device coupled to the heat sink.
Document U.S. Pat. No. 5,002,123 A describes a fluid heat exchanger for cooling an electronic component. The described solution comprises a plurality of spaced fins connected to the base, such fins being separated by fluid channels, wherein the cross-sectional area of the channels decreases from the inlet to the outlet.
Document U.S. Pat. No. 6,671,172 B2 describes a heat sink comprising a plurality of cooling fins, arranged about a core and coupled to a cooling device. The heat sink fins may have different shapes. According to one solution, the fins are curved. In another solution, the fins are knicked. In still another solution, the fins are both curved and knicked.